Sciencemadness Discussion Board

aniline derivatives

atomicfire - 7-6-2011 at 09:20

I am searching for a method to add a hydroxyl group in the ortho position on aniline. Does anyone know a productive method for this?

ScienceSquirrel - 7-6-2011 at 09:25

This is best done the other way.
Take phenol, nitrate and reduce it to form the aniline.
Most syntheses of phenolic compounds start from a phenol and add the other substituents as it is the easiest way.

atomicfire - 7-6-2011 at 09:38

Could one convert the hydroxyl to a carboxilic acid?

And also, wouldn't the nitrosation occur at the para position not the ortho?

[Edited on 7-6-2011 by atomicfire]

ScienceSquirrel - 7-6-2011 at 09:45

Converting a phenol to a carboxylic acid is fiendishly hard.
The phenol will direct nitration to the 2, 4 positions.
This is where organic chemists get cunning, often reaction conditions can be optimised to favour the one that you want eg

http://pubs.acs.org/doi/abs/10.1021/op0200120

or

http://www.oc-praktikum.de/en/instructions/pdf/5001_en.pdf

[Edited on 7-6-2011 by ScienceSquirrel]

atomicfire - 7-6-2011 at 10:56

My goal is to synthesize anthranilic acid.

So, if one were to start with benzoic acid could one add a nitro group then reduce it?

DJF90 - 7-6-2011 at 11:00

Anthranilic acid is typically formed by the hofmann degradation of phthalimide.

atomicfire - 7-6-2011 at 11:16

Yeah, I don't think I can get bromine for that reaction.

PHILOU Zrealone - 7-6-2011 at 13:02

Maybe try via
toluene -nitration-> o-nitrotoluene isolation (via diluted HNO3)
o-nitrotoluene -acidic oxydation-> o-nitrobenzoic acid (via KMnO4/H(+))
o-nitrobenzoic acid -reduction-> antranilic acid (o-aminobenzoic acid) (via Zn/HCl or SnCl2/HCl)

ScienceSquirrel - 7-6-2011 at 16:27

The easy mad chemist ways to anthranilic acid are from toluene as above or from phthalic acid from plasticisers.
If you wanted to start from aniline; you could make the nitroaniline, then do a Sandmeyer, hydrolyse to the nitrobenzoic acid and then reduce.
You cannot start from benzoic acid as the carboxyl group is 3 directing.
You need a starting material that is 2 directing or 1,2 substituted and then you want to do the chemistry that sets up your groups in the best way

DJF90 - 7-6-2011 at 16:42

ScienceSquirrel - off topic but are you (or anyone else) aware of a high yielding, direct reaction to 3-chlorobenzoic acid? I know benzoic acid *should* give the meta product upon chlorination, but all the literature I've seen so far describes a mixture of products.

gsd - 8-6-2011 at 07:55


Intra-Molecular Redox Reaction

o-Nitro Toluene ---------> o-Amino Benzoic acid (Anthranilic Acid)

Is this fantasy practically possible?

gsd

[Edited on 8-6-2011 by gsd]

ScienceSquirrel - 8-6-2011 at 09:16

Quote: Originally posted by DJF90  
ScienceSquirrel - off topic but are you (or anyone else) aware of a high yielding, direct reaction to 3-chlorobenzoic acid? I know benzoic acid *should* give the meta product upon chlorination, but all the literature I've seen so far describes a mixture of products.


I suspect that electrophilic substitution of benzoic acid will always give a mixture of isomers.